1. Field of the Invention
The present invention is concerned with a system for monitoring and responding to moisture leakage.
2. Description of the Related Art
Many of the appliances and fixtures in modern homes and commercial buildings are equipped with water supply lines. Because these lines occasionally develop leaks, water damage to floor coverings sub-floors and ceilings are becoming increasingly common. In particular, refrigerators, icemakers, dishwashers, washing machines, as well as sinks and toilets are subject to such leakage. Since water supply lines are usually placed behind and underneath appliances and fixtures for cosmetic purposes, any leakage from the lines or their couplings adjacent the water inlet, appliance valve or mechanism may not be discovered until an appliance is moved or the leak becomes sufficiently large to be visible from in front of the appliance or fixture. By the time such leakage becomes known, the water may well have caused damage to the floor covering, sub-floor, or a ceiling below.
Certain floor coverings such as, for example, wood surfaces are particularly vulnerable to water damage. Even a small leak under a refrigerator, such as a continuous intermittent drip, can cause damage to a wood flooring material or covering. Repair of damage to such surfaces typically involves replacing the damaged area followed by sanding and refinishing of the entire floor surface so that the finish on the new wood may be blended to conform to the finish on the remainder of the floor. Thus, leakage of even a relatively small quantity of moisture which goes undiscovered for a period of time can cause damage to a susceptible surface which eventually necessitates costly repairs. Certain appliances, such as refrigerator ice-making units, are particularly likely to leak and cause such damage at some time during the course of their usage because refrigerators are often moved periodically for cleaning of the floor surface beneath them.
Other types of floor coverings are also susceptible to moisture damage. For example, water which seeps underneath vinyl or tile floor coverings can cause damage which is not immediately detectable. Such seeped moisture may be wicked along beneath the floor covering for a substantial distance from the affected appliance. In addition, moisture which penetrates beneath any surface covering may cause damage to a wooden sub-floor and supporting joists as well as to adjacent to ceiling surfaces below.
While previous moisture leak detection systems are well-suited for detecting a continuous substantial leak, they are not capable of detecting slow or intermittent leakage of a very small quantity of moisture, such as one or two drops to a concealed space such as the floor surface beneath an appliance. Previous systems also require permanent placement of sensors beneath flooring surfaces, which is both expensive and inflexible. Such systems provide relatively small sensing areas, leaving other areas in the vicinity unprotected.
Consequently, there is a need for a small, relatively inexpensive device that can be placed under or behind appliances and fixtures to provide a relatively large moisture sensing area as soon as a leak begins and alert the homeowner, thus allowing the leak to be fixed before any water damage has occurred to the floor covering. This device would allow the homeowner to fix a leak while it was still small and thereby avoid the possibility of the leak suddenly getting much larger and causing extensive damage, as, for example, by flooding a room.
The present invention provides a leakage response system for an appliance including a sensor strip or mat which can be installed unobtrusively in areas prone to moisture leakage for prompt detection of minute quantities of moisture and a controller unit for actuation of a remote alarm and/or a water supply line shut-off valve before damage can occur to a floor covering.
In more detail, the system includes a leakage sensor strip which is operative to change an electrical parameter upon contact by a conductive liquid, a controller circuit electrically coupled with the strip for generating an activation signal in response to contact of the strip by a conductive liquid and a response device coupled with the controller circuit and activated by the signal. The sensor strip is constructed of top and bottom outer layers of electrically conductive fabric separated by a central nonconductive fabric layer; and a pair of fusing layers fusing the top and bottom layers to the central nonconductive layer. The response device may include an audible alarm and/or a valve for shutting off the water flow in the appliance water supply line. The response device may also include a radio transmitter for activating a remote alarm and shut off valve.